1. Field
Disclosed herein are antenna cores and antennas, as they are used in recognition systems, e.g., in keyless entry systems. Such recognition systems can be used in the most varied technical applications. Locking systems in automotive applications, entry control systems for safety-relevant areas, etc., can be mentioned only by way of example.
2. Description of Related Art
The antenna cores or antennas are used as transmitting antennas for generating a magnetic field. The antennas are generally operated in a resonant oscillating circuit, which is tuned by matching a series capacitor and/or a series resistor to the impedance of the antenna arrangement at the desired transmitting frequency. In this case, antennas with the highest possible quality are usually used, which, however, requires a high expense for the tuning of the resonance circuit.
In the simplest case, such a transmitting antenna can be designed with a ferrite rod core of any cross-section. Due to the high isotropic volume resistance of this magnetic material alone, high quality and low magnetism reversal losses are achieved with no special additional measures.
It may be necessary, however, for the constructed space available for the accommodation of the antenna to limit the antenna cross-section and/or to require a bent or bendable antenna. Because of their poor elasticity and the material-typical low saturation induction, ferrite rods are therefore unsuitable.